Stability ball circles

Place your forearms on a stability ball and extend your legs behind you, hip-width apart. Brace your abs and raise yourself into a plank position (A). Using your forearms, roll the ball out to the left, in front of you, and back to the right (like a stirring motion) and then pull it back into the starting position (B). That's one rep. Do 8 to 12, then switch directions and repeat.